PaxVax Announces Positive Results for Oral Ad4 Vaccine Technology

Phase One Study of Oral Replicating Vaccine for H5N1
Published in Lancet Infectious Diseases

MENLO PARK, Calif.--(BUSINESS WIRE)--Jan 31, 2013 - PaxVax,
Inc., which develops and commercializes innovative vaccines against
infectious diseases in a socially responsible manner, today
announced positive results in a Phase 1 clinical trial for its
oral, replicating adenovirus serotype 4 (Ad4) vector vaccine for
H5N1 (avian flu). The results have been published in the journal
Lancet Infectious Diseases (published online January 29,
2013). The study was funded by The Wellcome Trust.

The goals of this Phase 1 study were to evaluate the safety and
immunogenicity of the Ad4-H5-Vtn candidate vaccine, and, more
generally, to evaluate the replication-competent Ad4 as an orally
administered vector vaccine platform. The authors found the
Ad4-H5-Vtn vector vaccine was well tolerated and induced cellular
immune responses to the H5 HA. Subsequent boosting with a single
dose of a licensed inactivated H5N1 vaccine led to high rates of
seroprotection (HAI ‰¥ 40), significantly higher than in
placebo recipients receiving a single dose of H5N1 vaccine
(p<0.001).

“We are pleased to share these promising results from the
first clinical trial of our oral Ad4 technology,” said Marc
Gurwith, M.D., Chief Medical Officer of PaxVax. “In addition
to demonstrating initial proof of concept in H5N1, this study
demonstrates the potential ability of an oral Ad4 vector-based
vaccine as part of a prime/boost regimen to generate more robust
antibody responses than traditional vaccine
methodologies.”

PaxVax's vaccine vector technology such as the Ad4-H5-Vtn
vaccine is based on the existing licensed Adenovirus serotypes 4
and 7 (Ad4 and Ad7) vaccines, currently used by the U.S. Military.
These Ad4 and Ad7 vaccines have a substantial safety experience
having been administered to more than 10 million recruits without
significant adverse experience.

Kenneth Kelley, Chief Executive Officer of PaxVax commented:
“We are excited by these results in H5N1 and will continue to
develop this vaccine to potentially add another option for defense
against avian influenza pandemics. These Phase 1 results also
provide support for the Ad4 (and Ad7) oral replicating virus vector
approach. PaxVax will pursue other vaccine candidates for different
disease targets using this technology.”

To date, PaxVax has bioengineered dozens of vaccine candidates
using the Ad4 and Ad7 vector technology. Under NIH supported
programs, a number of different Ad4 vector vaccine candidates for
HIV and for anthrax have advanced into additional pre-clinical
development and animal studies, and are scheduled for Phase 1
clinical trials in 2013. Other vectors that have been constructed
and are potential vaccine candidates for further development
include Ad4 vectors expressing immunogens for herpes, influenza and
rabies viruses. The company has filed for patents to protect the IP
involved in developing these replication competent, oral vector
vaccines.

PaxVax is a privately held company committed to developing
better vaccines to better the world. Established in 2007, PaxVax
has a clinical-stage product portfolio, including a cholera vaccine
entering Phase 3 and a pandemic H5N1 influenza vaccine entering
Phase 2. The company also has vaccines in development for HIV and
anthrax under R&D contracts with NIH. The company's proprietary
adenoviral-based technology platform enables the rapid development
of oral vaccines that can target any viral or bacterial protein
antigen. The company's vaccine candidates are designed to be easier
to manufacture, store, distribute, administer and deliver across
the globe than conventional injectable vaccines while enhancing the
desired immune response to the vaccine antigens. The company's
offices are headquartered in Menlo Park, Calif., and the R&D
laboratories and licensed GMP production facility are based in San
Diego, Calif.

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